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SubjectRe: [PATCH v2 0/4] additional TPM performance improvements
On Wed, Sep 06, 2017 at 08:56:35AM -0400, Nayna Jain wrote:
> After further discussions with the Device Driver working group (ddwg),
> the following changes were made:
>
> * Check for burstcount at least once to confirm the TPM is ready to accept
> the data. Similarly, query for the TPM Expect status as sanity check at
> the end.
>
> * Make the sleep for status check during send() in the loop less than
> 5msec.
>
> * Make the sleep in the loop while querying for burstcount less than
> 5msec.
>
> Below is the list of patches along with the performance improvements
> seen with a TPM 1.2 with an 8 byte burstcount for 1000 extends:
>
> Patch |Improvement(time in sec)
>
> tpm: ignore burstcount to improve tpm_tis | ~41 - ~14
> send() performance.
>
> tpm: define __wait_for_tpm_stat to specify | ~14 - ~10
> variable polling sleep time
>
> tpm: reduce tpm_msleep() time in | ~10 - ~9
> get_burstcount()
>
> tpm: modify tpm_msleep() function to have | ~9 - ~8
> max range
>
> Changelog v2:
>
> * Add module parameter to handle ignoring of burst count during
> tpm tis send() operation.
> * Add improvements over sleep time to reduce delays.
>
> Nayna Jain (4):
> tpm: ignore burstcount to improve tpm_tis send() performance.
> tpm: define __wait_for_tpm_stat to specify variable polling sleep time
> tpm: reduce tpm_msleep() time in get_burstcount()
> tpm: use tpm_msleep() value as max delay
>
> Documentation/admin-guide/kernel-parameters.txt | 8 ++++++
> drivers/char/tpm/tpm-interface.c | 15 ++++++++--
> drivers/char/tpm/tpm.h | 7 +++--
> drivers/char/tpm/tpm_tis_core.c | 37 +++++++++++++++++++------
> 4 files changed, 53 insertions(+), 14 deletions(-)
>
> --
> 2.13.3
>

I'll look into this after next week.

/Jarkko

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